Back to Volume
Paper: Light-Time Effects, Multimode Pulsations and Binarity
Volume: 335, The Light-Time Effect in Astrophysics: Causes and Cures of the O - C diagram
Page: 85
Authors: Breger, M.
Abstract: The determination of O – C variations in single-period, large-amplitude pulsating stars can be considered a standard technique. We extend the method to multiperiodic, small-amplitude pulsators with as many as 60 simultaneously excited pulsation modes. The derived O – C variations are reliable if three conditions are met: (i) the multifrequency solution describes the observed light variations well, even if it is not complete, (ii) the observations cover many months for at least one year, (iii) the pulsation of the star is stable over the time interval examined.

The method is demonstrated for two δ Scuti variables. For the θ2 Tau binary system, the light-time shifts found for the low frequencies agree with those predicted for the primary, while the shifts for the high frequencies are compatible with the fainter secondary. For FG Vir, the phasing is constant to a few seconds over the two years covered.

Finally, the problem of very close frequencies is discussed.

Back to Volume